1. Field of the Invention
The present invention relates to an indicator, for example, to an indicator for presenting an output value as an analog meter value.
2. Description of the Related Art
Indication of a measured value by using a meter is widely performed. Due to recent advancement of digitalization, examples of a meter portion of such a measuring device include a meter portion realizing digital display of a measured numerical value, and a meter portion simulatory displaying an indicator on a liquid crystal display. However, there are many users who supports a meter portion in which indication is physically performed by an indicator needle on a scale plate, and a great number of the meter portions of this construction is manufactured even now.
A conventional meter portion will be described with reference to FIG. 9. FIG. 9A is a front view of the meter portion, and FIG. 9B is a side view thereof.
A meter portion 103 is used, for example, for a tuning device, and displays a pitch level or the like by an indication angle of an indicator needle 113 in an analogue fashion.
A permanent magnet 117 is fixed to a zero arm 153. A portion where the fixing is performed is not shown. The permanent magnet has a cylindrical shape and is magnetized in a direction perpendicular to a central shaft 118.
A coil 115 is wound around the permanent magnet 117 such that a magnetic field is generated in the direction perpendicular to the central shaft 118. The coil 115 is supported so as to be rotatable together with the indicator needle 113 about the central shaft 118.
On sides of both surfaces of the coil 115, in spaces between ends of the zero arm 153 and the coil 115, a first spiral spring 111 and a second spiral spring 112 are respectively arranged so as to be coaxial with the central shaft 118.
One end of the first spiral spring 111 is connected to a connection terminal 123 provided on the zero arm 153 and the other end thereof is connected to a connection terminal 124 provided on the coil 115.
On the other hand, one end of the second spiral spring 112 is connected to a connection terminal 121 provided on the zero arm 153 and the other end thereof is connected to a connection terminal 122 provided on the coil 115.
Both the first spiral spring 111 and the second spiral spring 112 urge the coil 115 in a direction opposite to a direction in which the indicator needle 113 swings.
The first spiral spring 111 and the second spiral spring 112 function as flow passages for supplying a current to the coil 115. The flow passage of the current is formed of a circuit including the connection terminal 123, the first spiral spring 111, the connection terminal 124, the coil 115, the connection terminal 122, the second spiral spring 112, and the connection terminal 121 in the stated order.
When the current flows through the coil 115, there is generated a torque for rotating the coil 115 about the central shaft 118 due to the magnetic field of the permanent magnet 117. The indicator needle 113 stops at apposition where the torque is balanced with an urging force of the first spiral spring 111 and the second spiral spring 112.
Recent development in thinning of the measuring device involves an increasing demand for a thinner meter portion. For the thinning technique, there is proposed an indicator disclosed in Japanese Utility Model Application Laid-open No. 62-34370.
According to this technique, the coil 115 is formed through printing on a substrate, thereby making the coil 115 thin.
However, with this technique, it is difficult to manufacture the coil 115 which satisfies conditions such as a torque. Therefore, the indicator with this technique has not been put into practical use.